1. Field of the Invention
The present invention relates to television receivers and in particular to means or circuits for adapting a television receiver for remote control.
2. Description of the Prior Art
It is well-known in the prior art to provide a remote control unit or apparatus for a television (TV) receiver, whereby signals may be transmitted from a point remote of the television receiver, typically by ultrasonic waves to the television receiver, to change the channel or to vary the volume of the audio program, as well as to turn on or off the TV receiver. Typically, such remote control apparatus includes a transducer or speaker capable of emitting ultrasonic waves which are directed toward the television receiver and are picked up by a microphone or transducer responsive to such ultrasonic waves, such ultrasonic waves then being converted into electrical signals capable of modifying the aforenamed functions within the TV receiver. Typically in the prior art, the microphone or transducer is permanently built into the TV receiver, along with the necessary amplification circuitry for amplifying and adapting the output of the receiver's microphone or transducer to permit the electrical signal to be of an appropriate form to be applied to the various portions of the TV chassis, e.g. UHF-VHF tuner, the audio amplifier, etc.
Typically, if it were desired to provide a TV receiver capable of remote control, it was necessary to permanently incorporate the microphone or transducer, as well as the adapting amplifier, within the TV receiver. Alternatively, if it were desired to market a TV receiver capable of being adapted for remote control at a later time, it was typically necessary in the prior art to require a rather complicated, extensive modification of the television receiver, as by a television technician. Typically, such adaptation of a television receiver to permit remote control, is beyond the normal capability of the average viewer. Thus, the present invention is particularly directed toward providing a television receiver that is readily adapted, by the average viewer without the use of any tools, to modify the set as by the insertion of an adaptor that will permit the remote control of the television receiver.
The above-identified application entitled "Selectively Coupled Synthesizer for Tuner of TV Receiver," describes a television receiver, and in particular a tuner of the varactor type, capable of being adapted for remote control. In particular, the above-described tuner includes a synthesizer selectively coupled during an initial period of operation to apply a tuning voltage to a varactor-type tuning circuit, and thereafter, the tuning voltage as developed by an automatic fine-tuning (AFT) circuit is applied to the tuner. The synthesizer circuit, as described in the above-identified application, comprises a keyboard, upon which the desired channel is selected to be stored within a channel memory. The output of the channel memory controls a programmable divider to divide the output of the tuner's local oscillator by a factor in accordance with the selected channel. The output of the programmable divider is phase-compared or mixed with the output of a reference oscillator, which is divided down by a fixed factor, to provide the desired tuning voltage. To select a particular channel, the synthesizer is actuated selectively for a relatively short period, during the initial period of operation, to develop the tuning voltage in accordance with the desired channel. Once the tuner has been tuned and such a desired channel has been selected, the AFT circuit is coupled to place a corresponding tuning voltage upon the tuner. Selectively-actuated switch means is responsive to energize the synthesizer circuit or the AFT circuit to operatively connect either of the foregoing circuits to the tuning circuit. The TV receiver as described in the above-identified application is readily adapted for remote control, as will be explained in accordance with the subject invention, whereby a channel is selected remotely and such information is carried by ultrasonic waves to the TV receiver, the signal being received by a transducer and decoded by a circuit within the tuner of the subject application, whereby the signal indicative of the desired channel is stored in the aforementioned memory.
In the adaptation of the receiver and in particular of the tuner as described in the subject application, it is necessary to ensure that the adaptation is relatively simple, whereby the average viewer may readily perform the adapting operation without the use of any tools. To this end, it is necessary that the number of electrical interconnections be simplified and that the power requirements to be applied to the remote control adaptor be relatively low to avoid possible shock hazards.